Unless you live on another planet or under a rock, you probably know by now how important exercise is to overall fitness and heart health.

It is a message that is hard to escape these days. There is plenty of research to suggest that exercise can reduce the risk of heart disease, stroke and some cancers. It can also help lower high blood pressure and lift your mood. And it has been shown to improve self-esteem and help with weight loss.

Yet despite the many studies backing the role exercise plays in heart health, a lot of adults aren't listening. Two-thirds of them are considered overweight and one-third fall into the obese category with a body mass index over 30.

For many, getting fit and healthy might seem like an unachievable goal, but experts say you don't have to spend hours in the gym to see the benefits of exercise.

A minimum of 30 minutes of cardio exercise can do the trick.

"It doesn't matter what type, as long as you do it," said Dr. Daniel Clearfield, Cowtown Medical director and a sports medicine and primary-care physician. "Ideally, you should do it five days a week but even two is beneficial."

Casual exercising is not going to do the trick, said Dr. Benjamin Levine, director of the Institute of Exercise and Environmental Medicine at UT Southwestern Medical Center and Texas Health Resources. It has to be something that you are committed to doing on a regular basis.

"Exercise should be part of hygiene, just like brushing your teeth," said Levine, who is also a professor of medicine and cardiology at UT Southwestern Medical Center.

Running and swimming are excellent. But cycling, walking on a treadmill or working out on an elliptical can also be beneficial. Even yoga or tai chi can make a difference if the workout is strenuous enough to elevate your heart rate.

Any combination of endurance exercises that get the large muscle groups moving is going to get results.

Whatever exercise you chose, you should be moving enough to produce a sweat. Runners should be moving at a clip that is fast enough to make talking possible but not easy. A Zumba class can get you the same results, if you are moving fast enough.

"Anything that gets your heart rate up, makes you sweat a little and makes you short of breath," Levine said.

To improve your overall health and keep your ticker pumping effectively, add strength and stretching exercises to a cardio routine one or two days a week. Yoga is great for stretching, and you can build strength with or without the use of weights.

Commit to exercising regularly and your body will respond.

The heart is a muscle, so you want to strengthen it, but you also want to tone the arteries around the heart, just like you would tone your arms, Clearfield said.

"When you work your biceps, you'll find it easier to lift things," he said. "It's the same thing with your heart."

With regular exercise, the heart starts pumping more efficiently and your stamina improves. That can pay off in big ways.

If someone is sedentary and one day has to run hard to catch a bus, he may end up having a heart attack, Levine says, as an example.

"But for someone who is fit, that's barely a blip," he said.

Although the younger you start exercising, the better, you are never too old to get into shape. Someone who is really committed to fitness when they are young could have a heart that is as youthful as a 30-year-old later in life.

If you start at 70, you won't be able to protect against arteriosclerosis but you can protect your heart against sudden death and see the health benefits of regular exercise, such as lower blood pressure, Levine said.

It takes about six weeks to start seeing an improvement in physical fitness, but the payoff continues over a lifetime, Clearfield said.

"Exercise is great at combating obesity and keeping the heart healthy," he said. "In the long run that can mean more years of life."

We asked three fitness pros from the Amon G. Carter Downtown YMCA to demonstrate three ways to kick off a healthy routine that includes cardio, strength and stretching.

Stretching

Yoga is one of the best ways to stretch the body, but a lot of people steer clear of this type of exercise because they are afraid it is just too hard to get into those pretzellike poses.

But you don't have to be limber like a rubber band to benefit from yoga. Poses can be modified, and most teachers are more than willing to do what it takes to make yoga accessible.

Yoga is all about focusing on your mat and not worrying about how flexible your neighbor is. The best way to enjoy the many heart-healthy benefits of yoga, including stress reduction and lower blood pressure, is to just do it.

"Yoga is how you get flexible," said Lisa Rodriguez, a trainer and instructor at the Downtown YMCA. "You don't have to start off flexible to do it."

Two to try at least twice a week:

1. Downward-facing dog

(Watch your dog stretch for hints on how to do this)

What it does: Strengthens shoulders and back. Stretches hamstrings and calves.

Kneel on all fours with your hands providing support and your fingers spread like starfish. Lift your hips so your tailbone is pointed toward the ceiling. Your body should be in an upside-down V shape. Shoulders should be down. Your hands and feet should be your foundation. If your hamstrings are less flexible, you can bend your knees to lift your hips up and back. Listen to your body and only stretch as far as you are comfortable.

2. Side gate

What it does: Increases strength, balance and flexibility. Opens hips.

What to remember: Maintain your alignment so you don't injure your rotator cuff.

From all fours, turn toward one side, bend one leg and use it for support. Raise the other leg, pushing the heel forward and keeping it flexed. Raise your arm to the ceiling, keeping your hand and shoulder aligned, fingers spread. Hold the position for a few seconds.

Strength

Lunge

What it does: Strengthens glutes, thighs and calves

What to remember: Keep your knee behind your toes when bending.

Standing tall, step forward with one leg, bending at the knee. Drop the other leg toward the floor, then slowly return to starting position. Repeat on the other side, working up to 12 reps. If this too easy, try holding light weights in each hand.

Pushup

What it does: Strengthens chest, triceps and shoulders.

What to remember: Keep core muscles tight

Start on all fours with your spine in a neutral position and hands spread wide apart. Drop toward the floor, keeping your spine straight. Repeat.

Cardio

Running

What it does: Improves endurance, stamina and heart health

What to remember: Start off slowly and gradually build up. You need to walk fast or run about 30 minutes five times a week for heart health.

For fitness, you need to move fast enough to sweat for 30 minutes.

For interval training, alternate between 1 to 2 minutes of running at 85 percent of your maximum heart rate and 2 to 3 minutes at 65 percent of your maximum heart rate. Repeat for up to 30 minutes.